Magento 404 is a Magento extension that allows you to customize 404 "page not found" errors to display related products as well as promotional products from a specific category instead of broken links.

Magento Google Maps is a module developed for e-merchants having multiple physical stores but only one online store. Its purpose extension is to provide users/visitors a proper landing page to locate/find the physical stores/outlets using advanced Google Maps features and get the directions to the location of the store. It features customer marker images, which allows store merchants to show the type of store/outlet through the images, and a popup block which appears on hovering over a map marker.

OpenOTP Authentication Plugin Magento enables strong two factor authentication for
admins and users.
It displays an overlay on a Challenge-Response session,
after filling in the username and password.
It manages an auto-create mode for local accounts on first login.
It will transparently handle any OpenOTP Login Mode, including
LDAP only,
OTP only, and
LDAP+OTP.

Magento Events Manager is a Magento extension for managing events. It allows a store owner to create events and sell tickets by associating products with respective events. Visitors can view the events in the form of a calendar, and can buy tickets for any upcoming event.

Magento Ajax Add To Cart is a Magento extension that makes it possible for customers to add, edit, or remove entries from their shopping cart during checkout or on any other page without reloading the page.

Abandoned Cart Reminder is a Magento extension that sends store visitors automatic follow-up emails about abandoned carts. Such emails attract customers to complete their checkout process and thus increase the chance of conversions. Merchants can attach discount coupons with the emails or any other promotional offers to make their reminder email more attractive. A direct link in the email takes the customer back to the same cart. Store admins can configure when to send emails, the number of reminders, and the time interval between them.

Additional Checkout Attributes (a.k.a. Magento order attributes) is a Magento extension that allows store owners to add custom fields to the checkout page. It is intended for for merchants dealing in products which require diverse information from customers in order to complete checkout process. It supports text, date, checkbox, and radio button inputs. It works with one-step checkout, has easy one click installation, and allows fields to be added to different products individually, as a group, or for all products.